1. Field of the Invention
The present invention relates to a movement detector which includes a rotating member which is rotatably connected to a base member, and a piezoelectric element for detecting various movements of the rotating member.
2. Description of the Related Art
An apparatus which detects a movement of an operating section etc. of an electronic equipment by using a piezoelectric element which converts a distortion, developed in a piezoelectric material layer when an external force is acted thereon, to an electric signal, has hitherto been known.
For example, in Japanese Patent Application Laid-open No. 2002-157063, a movement detecting apparatus which detects a movement of an operating lever which is used in a state of being connected to a PC (personal computer) etc. has been described. A lower surface of the operating lever is joined to a ceramics plate, and furthermore, a plurality of stress sensors is provided between a base portion and the ceramics plate. When the operating lever is moved in a horizontal direction (x, y direction), or in a direction of approaching to the base portion (+z direction: direction of pushing), an external force acting on each of the sensors is converted to an electric signal, and based on these signals, a movement of the operating lever in the horizontal direction and the pushing direction is detected. Moreover, there has been a mention that, it is possible to use a piezoelectric element as the sensors which detect the movement of the operating lever.
However, the movement detecting apparatus described in Japanese Patent Application Laid-open No. 2002-157063 is not capable of detecting all movements of the operating lever by a user. In other words, this movement detecting apparatus detects only a movement of the operating lever in the horizontal direction (x, y direction) and the pushing direction (+z direction), and is not structured to be capable of detecting a movement of the operating lever in a pulling direction (−z direction).
Furthermore, when a shape of an object of which the movement is to be detected, and a purpose of operation are different, the structure described in Japanese Patent Application Laid-open No. 2002-157063 is not applicable as it is. Particularly, when an object of which the movement is to be detected is a rotating member which is rotatably connected to a base member, and in a case of detecting a rotating movement, a movement of coming closer to/going away from the base member, or a twisting movement of the rotating operation, it is not possible to use a structure for detecting the movement of the operating lever described in Japanese Patent Application Laid-open No. 2002-157063, and it is necessary to use an appropriate structure in accordance with the movement of the rotating member.